Calculation of Optimal Geometrical Magnification and Spatial Resolution of Betatron Tomograph

One of the perspective directions of development of non-destructive testing is the method of computed tomography. Computed tomography really enhances the ability of X-ray inspection, from thin and simple to thick and complex parts. There are many factors that influence the performance of computed tomography, the main parameters for computed tomography scanners and also scanner based on betatron, are geometric magnification and spatial resolution. Calculations of these parameters for the betatron tomograph are shown in this paper

The Selection of Computed Tomography Scanning Schemes for Lengthy Symmetric Objects

The article describes the basic computed tomography scan schemes for lengthy symmetric objects: continuous (discrete) rotation with a discrete linear movement; continuous (discrete) rotation with discrete linear movement to acquire 2D projection; continuous (discrete) linear movement with discrete rotation to acquire one–dimensional projection and continuous (discrete) rotation to acquire of 2D projection. The general method to calculate the scanning time is discussed in detail. It should be extracted the comparison principle to select a scanning scheme. This is because data are the same for all scanning schemes: the maximum energy of the X–ray radiation; the power of X–ray radiation source; the angle of the X-ray cone beam; the transverse dimension of a single detector; specified resolution and the maximum time, which is need to form one point of the original image and complies the number of registered photons). It demonstrates the possibilities of the above proposed method to compare the scanning schemes. Scanning object was a cylindrical object with the mass thickness is 4 g/cm2, the effective atomic number is 15 and length is 1300 mm. It analyzes data of scanning time and concludes about the efficiency of scanning schemes. It examines the productivity of all schemes and selects the effective one

On subgroups in division rings of type 22

Let $D$ be a division ring with center $F$. We say that $D$ is a {\em division ring of type $2$} if for every two elements $x, y\in D,$ the division subring $F(x, y)$ is a finite dimensional vector space over $F$. In this paper we investigate multiplicative subgroups in such a ring.Comment: 10 pages, 0 figure

The Oxygen Abundance of Nearby Galaxies from Sloan Digital Sky Survey Spectra

We have derived the oxygen abundance for a sample of nearby galaxies in the Data Release 5 of the Sloan Digital Sky Survey (SDSS) which possess at least two independent spectra of one or several HII regions with a detected [OIII]4363 auroral line. Since, for nearby galaxies, the [OII]3727 nebular line is out of the observed wavelength range, we propose a method to derive (O/H)_ff abundances using the classic Te method coupled with the ff relation. (O/H)_7325 abundances have also been determined, based on the [OII]7320,7330 line intensities, and using a small modification of the standard Te method. The (O/H)_ff and (O/H)_7325 abundances have been derived with both the one- and two-dimensional t_2 - t_3 relations. It was found that the (O/H)_ff abundances derived with the parametric two-dimensional t_2 - t_3 relation are most reliable. Oxygen abundances have been determined in 29 nearby galaxies, based on 84 individual abundance determinations in HII regions. Because of our selection methods, the metallicity of our galaxies lies in the narrow range 8.2 < 12 + log (O/H) < 8.4. The radial distribution of oxygen abundances in the disk of the spiral galaxy NGC 4490 is determined for the first time.Comment: 39 pages, 10 figures, 4 tables, accepted for publication in the Astrophysical Journa

A HST study of the stellar populations in the cometary dwarf irregular galaxy NGC 2366

We present V and I photometry of the resolved stars in the cometary dwarf irregular galaxy NGC 2366, using Wide Field Planetary Camera 2 images obtained with the Hubble Space Telescope. The resulting color-magnitude diagram reaches down to I~26.0 mag. It reveals not only a young population of blue main-sequence stars (age <30 Myr) but also an intermediate-age population of blue and red supergiants (20 Myr<age<100 Myr), and an older evolved populations of asymptotic giant branch (AGB) stars (age >100 Myr) and red giant branch (RGB) stars (age >1 Gyr). The measured magnitude I=23.65+/-0.10 mag of the RGB tip results in a distance modulus m-M=27.67+/-0.10, which corresponds to a distance of 3.42+/-0.15 Mpc, in agreement with previous distance determinations. The youngest stars are associated with the bright complex of HII regions NGC 2363=Mrk 71 in the southwest extremity of the galaxy. As a consequence of the diffusion and relaxation processes of stellar ensembles, the older the stellar population is, the smoother and more extended is its spatial distribution. An underlying population of older stars is found throughout the body of NGC 2366. The most notable feature of this older population is the presence of numerous relatively bright AGB stars. The number ratio of AGB to RGB stars and the average absolute brightness of AGB stars in NGC 2366 are appreciably higher than in the BCD VII Zw 403, indicating a younger age of the AGB stars in NGC 2366. In addition to the present burst of age <100 Myr, there has been strong star formation activity in the past of NGC 2366, from ~100 Myr to <3 Gyr ago.Comment: 32 pages, 15 figures, accepted for publication in the Astrophysical Journa

Dynamic Three-Dimensional Imaging of Cellular Shape Changes and Protein Expression in the Developing Zebrafish Heart

We present our results in dynamic three-dimensional (3D) imaging and quantification of the cellular shape changes and gene expressions of the developing zebrafish heart, in the effort to understand the mechanisms of the embryonic construction of this critical organ. The vertebrate heart is built up through a series of steps taking two flat layers of cells to a hollow heart tube to a multi-layered, multi-chambered, chirally twisted structure of the mature organ. Additionally, the heart is the first organ in the developing embryo to function, through its beating and pumping of the blood, shortly after the formation of the heart tube. Despite this intrinsic dynamic 3D nature of the developing heart, previous works documenting its development consist of largely 2D and/or static imaging (utilizing pharmacological means to stop the beating of the heart), due to the challenges in achieving fast, high 3D-resolution with conventional imaging modalities. To overcome these challenges, we employ 2-photon light sheet microscopy and a wavelet-based synchronization and registration method to achieve the required spatial and temporal resolution to capture the 3D motion of the heart. The high speed 3D imaging and analysis is carried out on several transgenic zebrafish lines that have been recently generated in our lab where proteins important for heart development are fluorescently tagged at their endogenous loci. We thus document not only cellular morphology but also critical genes' expression, with sub-cellular resolution, of the developing heart, over its beating cycle and at different development times. These results provide the necessary groundwork to start deciphering the process where the dynamic changes in cellular shapes, gene expressions, and cellular physical properties participate, in concert with the genetic program, in the development of the vertebrate heart

Dynamic structure and protein expression of the live embryonic heart captured by 2-photon light sheet microscopy and retrospective registration

We present an imaging and image reconstruction pipeline that captures the dynamic three-dimensional beating motion of the live embryonic zebrafish heart at subcellular resolution. Live, intact zebrafish embryos were imaged using 2-photon light sheet microscopy, which offers deep and fast imaging at 70 frames per second, and the individual optical sections were assembled into a full 4D reconstruction of the beating heart using an optimized retrospective image registration algorithm. This imaging and reconstruction platform permitted us to visualize protein expression patterns at endogenous concentrations in zebrafish gene trap lines

Imaging the Beating Heart with Macroscopic Phase Stamping

We present a novel approach for imaging the beating embryonic heart, based on combining two independent imaging channels to capture the full spatio-temporal information of the moving 3D structure. High-resolution, optically-sectioned image recording is accompanied by simultaneous acquisition of low-resolution, whole-heart recording, allowing the latter to be used in post-acquisition processing to determine the macroscopic spatio-temporal phase of the heart beating cycle. Once determined, or 'stamped', the phase information common to both imaging channels is used to reconstruct the 3D beating heart. We demonstrated our approach in imaging the beating heart of the zebrafish embryo, capturing the entire heart over its full beating cycle, and characterizing cellular dynamic behavior with sub-cellular resolution

Checking the possibility of controlling fuel element by X-ray computerized tomography

The article considers the possibility of checking fuel elements by X-ray computerized tomography. The checking tasks are based on the detection of particles of active material, evaluation of the heterogeneity of the distribution of uranium salts and the detection of clusters of uranium particles. First of all, scheme of scanning improve the performance and quality of the resulting three-dimensional images of the internal structure is determined. Further, the possibility of detecting clusters of uranium particles having the size of 1 mm3 and measuring the coordinates of clusters of uranium particles in the middle layer with the accuracy of within a voxel size (for the considered experiments of about 80 [mu]m) is experimentally proved in the main part. The problem of estimating the heterogeneity of the distribution of the active material in the middle layer and the detection of particles of active material with a nominal diameter of 0.1 mm in the "blank" is solved